Non-uniform heat transfer suppression to enhance PCM melting by angled fins

We present numerical investigations on a thermal energy storage system with phase change materials (PCMs) vertically heated from one side of a rectangular enclosure. A transient numerical model is developed to study the heat transfer and melting behaviors, and the natural convection is accounted. To...

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Main Authors: Ji, Chenzhen, Qin, Zhen, Low, Zhenghua, Dubey, Swapnil, Choo, Fook Hoong, Duan, Fei
Other Authors: School of Mechanical and Aerospace Engineering
Format: Article
Language:English
Published: 2020
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Online Access:https://hdl.handle.net/10356/142737
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1427372021-01-13T02:23:42Z Non-uniform heat transfer suppression to enhance PCM melting by angled fins Ji, Chenzhen Qin, Zhen Low, Zhenghua Dubey, Swapnil Choo, Fook Hoong Duan, Fei School of Mechanical and Aerospace Engineering Energy Research Institute @ NTU (ERI@N) Engineering::Mechanical engineering Thermal Energy Storage Phase Change Materials We present numerical investigations on a thermal energy storage system with phase change materials (PCMs) vertically heated from one side of a rectangular enclosure. A transient numerical model is developed to study the heat transfer and melting behaviors, and the natural convection is accounted. To suppress the non-uniform heat transfer for the PCM melting enhancement, fins with the inclined angle of 0°,+15°,+30°,-15° and -30° are proposed. The melt fraction contours with the natural convection driven flow are performed and compared, as well as the temperature distributions. Results show that the fins in a downward angle of -15° accelerate the PCM melting faster than the others, as the part of heat is well transferred to the bottom of container along the fins and the original non-uniform melting caused by natural convection is reduced. Contrarily, the upward fins in +15° and +30° deepen the non-uniform heat distribution and slow down the melting. The saved PCM melting time is defined on the basis of the No Fin PCM case. It is found that saved melting time of PCMs with -15° fins increases 23.8% on the case of the 0° fins, while decreases 45.2% and 71.4% with the +15° and +30° fins. The fin length and heat flux input are also examined for the PCM melting. The fin length shows the significant influence on the PCM melting with the tilted fins. As the length ratio of fin to container increases to 0.75, the non-uniform melting is obviously suppressed due to the addition of the -15° fins, and temperature contours inside the PCM domain show much more uniform, by comparing with 0° fins. The PCM melting rate with -15° fins also increases greatly and the saved melting time rises about 62.7%. Besides, the enhancement ratio reveals that the melting enhancement by the fins mainly appears at the second half of the entire process, based on the PCM solid-liquid interface formed at the first half. NRF (Natl Research Foundation, S’pore) 2020-06-29T08:33:08Z 2020-06-29T08:33:08Z 2017 Journal Article Ji, C., Qin, Z., Low, Z., Dubey, S., Choo, F. H., & Duan, F. (2018). Non-uniform heat transfer suppression to enhance PCM melting by angled fins. Applied Thermal Engineering, 129, 269-279. doi:10.1016/j.applthermaleng.2017.10.030 1359-4311 https://hdl.handle.net/10356/142737 10.1016/j.applthermaleng.2017.10.030 2-s2.0-85030994544 129 269 279 en Applied Thermal Engineering © 2017 Elsevier Ltd. All rights reserved.
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Engineering::Mechanical engineering
Thermal Energy Storage
Phase Change Materials
spellingShingle Engineering::Mechanical engineering
Thermal Energy Storage
Phase Change Materials
Ji, Chenzhen
Qin, Zhen
Low, Zhenghua
Dubey, Swapnil
Choo, Fook Hoong
Duan, Fei
Non-uniform heat transfer suppression to enhance PCM melting by angled fins
description We present numerical investigations on a thermal energy storage system with phase change materials (PCMs) vertically heated from one side of a rectangular enclosure. A transient numerical model is developed to study the heat transfer and melting behaviors, and the natural convection is accounted. To suppress the non-uniform heat transfer for the PCM melting enhancement, fins with the inclined angle of 0°,+15°,+30°,-15° and -30° are proposed. The melt fraction contours with the natural convection driven flow are performed and compared, as well as the temperature distributions. Results show that the fins in a downward angle of -15° accelerate the PCM melting faster than the others, as the part of heat is well transferred to the bottom of container along the fins and the original non-uniform melting caused by natural convection is reduced. Contrarily, the upward fins in +15° and +30° deepen the non-uniform heat distribution and slow down the melting. The saved PCM melting time is defined on the basis of the No Fin PCM case. It is found that saved melting time of PCMs with -15° fins increases 23.8% on the case of the 0° fins, while decreases 45.2% and 71.4% with the +15° and +30° fins. The fin length and heat flux input are also examined for the PCM melting. The fin length shows the significant influence on the PCM melting with the tilted fins. As the length ratio of fin to container increases to 0.75, the non-uniform melting is obviously suppressed due to the addition of the -15° fins, and temperature contours inside the PCM domain show much more uniform, by comparing with 0° fins. The PCM melting rate with -15° fins also increases greatly and the saved melting time rises about 62.7%. Besides, the enhancement ratio reveals that the melting enhancement by the fins mainly appears at the second half of the entire process, based on the PCM solid-liquid interface formed at the first half.
author2 School of Mechanical and Aerospace Engineering
author_facet School of Mechanical and Aerospace Engineering
Ji, Chenzhen
Qin, Zhen
Low, Zhenghua
Dubey, Swapnil
Choo, Fook Hoong
Duan, Fei
format Article
author Ji, Chenzhen
Qin, Zhen
Low, Zhenghua
Dubey, Swapnil
Choo, Fook Hoong
Duan, Fei
author_sort Ji, Chenzhen
title Non-uniform heat transfer suppression to enhance PCM melting by angled fins
title_short Non-uniform heat transfer suppression to enhance PCM melting by angled fins
title_full Non-uniform heat transfer suppression to enhance PCM melting by angled fins
title_fullStr Non-uniform heat transfer suppression to enhance PCM melting by angled fins
title_full_unstemmed Non-uniform heat transfer suppression to enhance PCM melting by angled fins
title_sort non-uniform heat transfer suppression to enhance pcm melting by angled fins
publishDate 2020
url https://hdl.handle.net/10356/142737
_version_ 1690658498671542272